THE SENSES AND THEIR ORGANS. 



285 



Professor Wilder, when studying tlie liabits of Nephila plumiiics, ' caiue 



to tlie conclusion that spiders of that species cannot see anything at all, 



whether near or remote. I do not accept the conclusion, l)ut 



Vtt-^-^ give some facts on which it was based. Tlie siiiders iiaid no at- 

 of vision. . . 



tention to an object put close to them, nor to the quiet movements 



of any one about them. An individual would often rush by an insect en- 

 tangled in her net, if it chanced to cease its struggles before she had accu- 

 rately determined its position; she would then slowl}^ return to the centre 

 of the web, and wait until another vibration indicated the whereabouts 

 of the insect. A fly offered upon the point of a needle would not be no- 

 ticed until it began to buzz, when it would be seized at once. Nephila, 

 however, always prefers the light, and constructs her large orljs where the 

 sun can reach them. The young mani- > 



fest the same instinct, and in confine- 

 ment seek the sunny side of a glass 

 vessel. 



In order to test the ability of the 



Furrow spider to work upon her web 



without the aid of daylight, 



Orbs J secluded one within a large 



ti n k *^^^^ ^^^^^^ '^ sliding glass door. 

 She soon spun an orb web 

 across the cell as clo.se to the glass door ^.^^ 



and as far toward the light as could well Fig. 283. sagittal section through an anterior 



be. Fortunately not a line of the snare ■"""''" '"y"- "s^ht days after hatching; the 

 was attached to the glass itself, so that 

 I could draw it back and forth at will. 

 I next cut away the lower foundation 

 line, broke up the entire lower jiart of 

 the web, and the box was then completely darkened. Next day, when 

 the covers and screens were removed, the web was found thoroughly 

 mended, every part being so neatly and accurately repaired that it was 

 scarcely possible to determine which was the patchwork and which the 

 original snare. Even if we admit that some particle of light may have 

 entered the cell, the sense of ti)uch in this case must have Iseen the chief 

 reliance. 



In other experiments the spider's sight, in so far as that sense can be 

 apprehended by human experience, could have had no part in 

 Cocoon- tlirecting her work. I have repeatedly confined female Orbweav- 

 ers, Epeira strix, sclopetaria, insularis, domiciliorum, and triara- 

 nea, Acrosoma rugosa, and others, in paper boxes absolutely im- 

 pervious to light, and opening them the next day have found eggs deposited 



retinal portion has not yet readied its full 

 development. X about 350. Ins, lens : vit, 

 "vitreous body;" eta, cuticula ; hd, hypoder- 

 mis; rtn', first (inverted) layer of optic invag- 

 ination ; rtn", second (non inverted) layer. 

 (After Locy.) 



ing- m 

 the Dark 



1 Proceed. Boston Soc. Nat. Hist., Vol. X., page 208. 



